Faculty Profiles - ISHIKAWA, Yoshiharu

Papers - ISHIKAWA, Yoshiharu

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Processing Queries Including User - defined Foreign Functions on XML Views over Relational Databases Reviewed

Jun Kawada, Yoshiharu Ishikawa, and Hiroyuki Kitagawa

IPSJ Transactions on Databases Vol. 43 ( SIG 12(TOD 16) ) page： 16-37 2002.12

Language：Japanese Publishing type：Research paper (scientific journal)

XML views over RDBs and to allow users to access data with XML query languages such as XQuery.The query processing is done effciently by making the best of the querying power of RDBMSs.Namely,XML queries are translated into SQL queries and tagging operations, which are processed by the RDBMSs and, middleware,respectively.In some XML query languages including XQuery,use of user-de ?ned foreign functions is enabled or planned as an extension feature to cope with domain dependent semantics.Foreign functions are de ?ned for XML fragments,and their implementations are often given by codes in a general programming language.The existing query processing schemes on XML views do not consider cases where foreign functions are included in XML queries.In this paper,we propose extended schemes to process XML queries in such cases.In the proposed schemes,the middleware takes care of processing foreign functions as well as tagging operations.Therefore,the proposed schemes are applicable to XML views on commonly available RDBMSs.Three types of query processing schemes are proposed,and their performance is studied with experiments.

Continual Neighborhood Tracking for Moving Objects Using Adaptive Distances Reviewed

Yoshiharu Ishikawa, Hiroyuki Kitagawa, and Tooru Kawashima

Proceedings of the International Database Engineering and Application Symposium (IDEAS'02) page： 54-63 2002.7

Authorship：Lead author Language：English

Based on the recent progress of digital cartography, global positioning systems (GPSs), and hand-held devices, there are growing needs of technology that provides neighborhood information to moving objects according to their locations and trajectories. In this paper, we propose spatial query generation models that take account of the current position and the past/future trajectories of a moving object to provide appropriate neighborhood information to it. For this purpose, we introduce an influence model of trajectory points and derive neighborhood query generation models using adaptive ellipsoid distances. We describe query processing strategies for these query generation models and show incremental query update procedures to support continual query facilities with low processing cost. Finally, we present experimental results to show the effectiveness of our approach.

配信型情報源統合環境における統合演算の共有 Reviewed

渡辺陽介, 北川博之, 石川佳治

情報処理学会・電子情報通信学会情報・システムソサイエティ共催第1回情報科学技術フォーラム (FIT2002) 情報技術レターズ Vol. 1 page： 65-66 2002.9

Transforming XPath Queries for Bottom-Up Query Processing Reviewed

Yoshiharu Ishikawa, Takaaki Nagai, and Hiroyuki Kitagawa

Proceedings of the IASTED Interanational Conference on Information Systems and Databases (ISDB 2002) page： 210-215 2002.9

Authorship：Lead author Language：English

The widespreading of XML as a content-description language
on the Web requires advanced processing and
management techniques for huge XML databases. XPath
is a standard language for extracting the specified elements
from XML documents, and its efficient support
is one of the key issues in the current XML database
technology. In this paper, we propose an XPath query
transformation method for the efficient query processing.
It transforms top-down, navigation-based XPath queries
into equivalent bottom-up query plans by using schema
information. Based on this technique, we can achieve efficient
set-oriented processing of XPath queries with the
support of index mechanisms.

VIDI: Visual Specification for Integration of Distributed Dissemination-based Information Sources Reviewed

Yousuke Watanabe, Yoshinori Okamoto, Hiroyuki Kitagawa, and Yoshiharu Ishikawa

Proceedings of the IASTED International Conference on Network, Parallel and Distributed Processing, and Applications (NPDPA 2002) page： 217-222 2002.9

Integration of Multiple Dissemination-Based Information Sources Using Source Data Arrival Properties and Validation of Integration Requirements Reviewed

Yousuke Watanabe, Hiroyuki Kitagawa, and Yoshiharu Ishikawa

IEICE Transactions on Inforamtion and Systems (Japanese Edition) Vol. J85-DI ( 12 ) page： 1126-1141 2002.12

Processing XML View Queries Including User-defined Foreign Functions on Relational Databases Reviewed

Yoshiharu Ishikawa, Jun Kawada, and Hiroyuki Kitagawa

Proceedings of the 3rd International Conference on Web Information Systems Engineering (WISE 2002) page： 225-236 2002.12

Authorship：Lead author Language：English

With the increased popularity of XML, XML publishing of RDBs has been attracting a lot of research interests. One of typical approaches is to use a middleware system to render XML views over RDBs and to allow users to access data with XML query languages such as XQuery. The query processing is done efficiently by making the best of the querying power of RDBMSs. Namely, XML queries are translated into SQL queries and tagging operations, which are processed by the RDBMSs and middleware, respectively. In some XML query languages including XQuery, use of user-defined foreign functions is enabled or planned as an extension feature to cope with domain dependent semantics. Foreign functions are defined for XML fragments, and their implementations are often given by codes in a general programming language. The existing query processing schemes on XML views do not consider cases where foreign functions are included in XML queries. In this paper, we propose extended schemes to process XML queries in such cases. In the proposed schemes, the middleware takes care of processing foreign functions as well as tagging operations. Therefore, the proposed schemes are applicable to XML views on commonly available RDBMSs. Three types of query processing schemes are proposed, and their performance is studied with experiments.

ignature-based Object Retrieval in Peer-to-Peer Environments Reviewed

Ryo Matsushita, Hiroyuki Kitagawa, and Yoshiharu Ishikawa

IPSJ Transactions on Databases Vol. 44 ( SIG 12(TOD 19) ) page： 139-149 2003.9

Language：Japanese Publishing type：Research paper (scientific journal)

Peer-to-peer (P2P) technology has attracted a lot of attention in recent years. Efficient object retrieval is an important research issue in P2P environments, especially in those without centralized global indices. Although a number of hash-based basic object retrieval schemes are known to alleviate the problem, they cannot provide flexible feature-based object search. In this paper, we propose a novel object retrieval method using distributed frame sliced signatures, and evaluate its effectiveness with simulation experiments.

An Efficient Mobility Statistics Extracting Method for Indexed Spatio-Temporal Datasets Reviewed

Yuichi Tsukamoto, Yoshiharu Ishikawa, and Hiroyuki Kitagawa

DBSJ Letters Vol. 2 ( 1 ) page： 27-30 2003.5

Language：Japanese Publishing type：Research paper (scientific journal)

With the recent progress of spatial information technologies
and mobile computing technologies, spatio-temporal databases
which store information on moving objects including vehicles
and mobile users have gained a lot of research interests. In this
paper, we propose an algorithm to extract mobility statistics
from indexed spatio-temporal datasets for the interactive
analysis of huge collections of moving object trajectories. We
focus on a mobility statistics value called the Markov transition
probability, which is based on a cell-based organization of a
target space and the Markov chain model. The proposed
algorithm efficiently computes the specified Markov transition probabilities with the help of a spatial index R-tree. We reduce
the statistics computation task to a kind of constraint
satisfaction problem that uses a spatial index, and utilize
internal representation of R-tree in an efficient manner.

Evaluation of a Mobility Statistics Extraction Scheme for Indexed Spatio-Temporal Datasets Reviewed

Yuichi Tsukamoto, Yoshiharu Ishikawa, and Hiroyuki Kitagawa

DBSJ Letters Vol. 2 ( 2 ) page： 21-24 2003.10

Language：Japanese Publishing type：Research paper (scientific journal)

With the recent progress of spatial information technologies and mobile computing technologies, spatio-temporal databases which store information on moving objects including vehicles and mobile users have gained a lot of research interests. Here we focus on a mobility statistics value called the Markov transition probability, which is based on a cell-based organization of a target space and the Markov chain model. We have proposed an algorithm to extract mobility statistics from indexed spatio-temporal datasets for the interactive analysis of huge collections of moving object trajectories. The proposed algorithm efficiently computes the specified Markov transition probabilities with the help of a spatial index R-tree. In this paper, we evaluate the effectiveness of proposed method based on an experiment.

An Improved Approach to the Clustering Method Based on Forgetting Factors Reviewed

Yoshiharu Ishikawa and Hiroyuki Kitagawa

DBSJ Letters Vol. 2 ( 3 ) page： 53-56 2003.12

Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal)

Clustering plays important roles in various on-line
applications such as extraction of useful information from
news feeding services and selection of relevant documents
from incoming scientific articles in digital libraries. In
on-line environments, users generally have interests on
newer documents than older ones and have no interests
on obsolete old documents.
Based on this observation, we have proposed an on-line
document clustering method that incorporates the notion
of a forgetting factor to calculate document similarities.
The idea is that every document gradually losses its
weight (or memory) as time passes according to this factor.
Since our method generates clusters using a document
similarity measure based on the forgetting factor, newer
documents have much effect on the resulting cluster
structure than older ones. In this paper, we extend our
clustering method by using the K-means clustering
algorithm as its basis. The new algorithm has clear
semantics and supports incremental updates of cluster
structures.

Implementation and Evaluation of an Adaptive Neighborhood Information Retrieval System for Mobile Users Reviewed

Yoshiharu Ishikawa, Yuichi Tsukamoto, and Hiroyuki Kitagawa

Proceedings of the 3rd International Workshop on Web and Wireless Geographic Information Systems (W2GIS) page： 25-33 2003.12

Authorship：Lead author Language：English

Rapid development and ongoing research activities on
mobile devices, digital cartography, and global positioning
systems (GPSs) have brought us a new type of software
service―location-based services for moving objects (such
as people with mobile devices and vehicles with car navigation
systems). Realization of location-based services requires
new technologies to provide appropriate neighborhood
information to moving objects. A general approach
to providing neighborhood information to moving objects
is to retrieve objects in the neighborhood of a moving object
with a spatial query that uses the traditional Euclidean
distance. However, if we know the destination and the estimated
route of a moving object, we would be able to provide
more appropriate information to the object. Based on
this idea, we have developed adaptive spatial query generation
models that take the trajectory of a moving object into
consideration to retrieve desired information. In this paper,
we describe the design and implementation of the neighborhood
information retrieval system based on the models and
evaluate its effectiveness with experiments.

Requirement Specification and Derivation of ECA Rules for Integrating Multiple Dissemination-Based Information Sources Invited Reviewed

Tomoaki Kajino, Hiroyuki Kitagawa, and Yoshiharu Ishikawa

IEICE Transactions on Information and Systems Vol. E87-D ( 1 ) page： 3-14 2004.1

Language：English Publishing type：Research paper (scientific journal)

The recent development of network technology has enabled us to access various information sources easily, and their integration has been studied intensively by the data engineering research community. Although technological advancement has made it possible to integrate existing heterogeneous information sources, we still have to deal with information sources of a new kind--dissemination-based information sources. They actively and autonomously deliver information from server sites to users. Integration of dissemination-based information sources is one of the popular research topics. We have been developing an information integration system in which we employ ECA rules to enable users to define new information delivery services integrating multiple existing dissemination-based information sources. However, it is not easy for users to directly specify ECA rules and to verify them. In this paper, we propose a scheme to specify new dissemination-based information delivery services using the framework of relational algebra. We discuss some important properties of the specification, and show how we can derive ECA rules to implement the services.

Development and Evaluation of a Spatial Database Retrieval System to Provide Neighborhood Information to Moving Objects Reviewed

Yuichi Tsukamoto, Yoshiharu Ishikawa, and Hiroyuki Kitagawa

IEICE Transactions on Information and Systems (Japanese Edition) Vol. J87-DI ( 2 ) page： 202-215 2004.2

Feature-based Distributed Object Search Using Signatures in Peer-to-Peer Environments Reviewed

Ryo Matsushita, Hiroyuki Kitagawa, and Yoshiharu Ishikawa

Proceedings of the 19th Annual ACM Symposium on Applied Computing (SAC 2004) page： 729-734 2004.3

Language：English

Peer-to-Peer (P2P) technology has attracted a lot of attention in recent years. Efficient object search is an important research issue in P2P environments, especially in those without centralized global indexes. Although a number of hash-based basic object search schemes are known to alleviate the problem, they cannot provide flexible feature-based object searches. This paper proposes a novel object search method using distributed frame sliced signatures, and looks at an appropriate choice of parameters to adapt the configuration to the object search and registration workload. It shows object search and registration schemes that take into account the number of messages and response times. Effectiveness of these schemes is evaluated through simulation experiments.

Exracting Mobility Statistics from Indexed Spatio-Temporal Databases Reviewed

Yoshiharu Ishikawa, Yuichi Tsukamoto, and Hiroyuki Kitagawa

Proceedings of the 2nd Workshop on Spatio-Temporal Database Management (STDBM'04) page： 9-16 2004.8

Authorship：Lead author Language：English

With the recent progress of spatial information
technologies and mobile computing technologies,
spatio-temporal databases that store information of
moving objects have gained a lot of research interests.
In this paper, we propose an algorithm
to extract mobility statistics from indexed spatiotemporal
datasets for interactive analysis of huge
collections of moving object trajectories. We focus
on mobility statistics called the Markov transition
probability, which is based on a cell-based organization
of a target space and the Markov chain model.
The algorithm computes the specified Markov transition
probabilities efficiently with the help of an Rtree
spatial index. It reduces the statistics computation
task to a kind of constraint satisfaction problem
and uses internal structure of an R-tree in an efficient
manner.

An Incremental Update Method for Materialized XSLT Views on RDBs Reviewed

Yoshiharu Ishikawa, Shusaku Miyasaka, and Hiroyuki Kitagawa

DBSJ Letters Vol. 3 ( 2 ) page： 25-28 2004.9

Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal)

In information systems which provide XML documents,
RDBs are often used for data storage and XML
generation. XML documents in these systems can be
seen as database views. In this paper, we assume
an environment such that a client can define XML
views using XSLT over a remote relational database
and XML views are materialized on the client. We
propose an efficient method for updating materialized
XML views in an incremental manner. In our
approach, the view management system analyzes a
database schema and XSLT view definitions, and generates
update scripts. When a new update occurs, the
scripts are executed for XML view updates.

Web Link Analysis for Extracting SpatialInformation Hub Pages

Jianwei Zhang, Yoshiharu Ishikawa, and Hiroyuki Kitagawa

DBSJ Letters Vol. 3 ( 3 ) page： 9-12 2004.12

Language：Japanese Publishing type：Research paper (scientific journal)

Recently web mining that tries to find relevant information
from the vast amount of web pages has attracted
a lot of research interests. Besides, it is becoming
an important task to provide information related
to a user-specified geographic area. In this paper,
we propose a method to extract spatial information
hub pages. A spatial information hub is a webpage
which is related to a specified geographic area
and has much local information or many hyperlinks
to local web pages. We employ geographic information
to create spatial nodes and spatial links, and then conduct
link analysis based on the extended link structure.

Extended Link Analysis for Extracting Spatial Information Hubs

Jianwei Zhang, Yoshiharu Ishikawa, and Hiroyuki Kitagawa

Proceedings of International Workshop on Challenges in Web Information Retrieval and Integration (WIRI 2005) page： 17-22 2005.4

Language：English

Recently, web mining that tries to find useful knowledge from the vast amount of web pages has attracted a lot of research interests. Besides, it is becoming an essential task to provide web pages related to a user-specified geographic area. In this paper, we propose an approach to extract spatial information hubs from the web. A spatial information hub is a web page which is related to a specified geographic area and has much local information and/or many hyperlinks to local web pages. In the traditional approach of web link analysis, the importance and quality of pages are judged only by their contents and hyperlink structures. However, we take their geographic localities into consideration. In our approach, we first extract geographic information from web pages to create spatial nodes and spatial links, then conduct a link analysis based on the extended link structures. We also show our approach works well based on the experiments.

LocalRank: Ranking Web Pages Considering Geographical Locality by Integrating Web and Databases Reviewed

Jianwei Zhang, Yoshiharu Ishikawa, Sayumi Kurokawa, and Hiroyuki Kitagawa

Proceedings of the 16th International Conference on Database and Expert Systems Applicatioins (DEXA 2005) page： 145-155 2005.8

Language：English

In this paper, we propose a method called LocalRank to rank web pages by integrating the web and a user database containing information on a specific geographical area. LocalRank is a rank value for a web page to assess its relevance degree to database entries considering geographical locality and its popularity on a local web space. In our method, we first construct a linked graph structure using entries contained in the database. The nodes of this graph consist of database entries and their related web pages. The edges in the graph are composed of semantic links including geographical links between these nodes, in addition to conventional hyperlinks. Then a link analysis is performed to compute a LocalRank value for each node. LocalRank can represent user's interest since this graph effectively integrates the web and the user database. Our experimental results for a local restaurant database shows that local web pages related to the database entries are highly ranked based on our method.

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Papers - ISHIKAWA, Yoshiharu